What is used to prevent duplicate processing of Kafka messages?

Question

Options

• AOffset value
• BSequential queues
• CDeleting messages
• DRetention periods

• A
  76% (35)
• B
  7% (3)
• C
  15% (7)
• D
  2% (1)

Explanation

Kafka uses offset values (A) to track which messages a consumer has already processed - each message in a partition has a unique, sequential offset number, and consumers commit their current offset to remember their position. If a consumer restarts, it resumes from the last committed offset, avoiding reprocessing.

Why the distractors are wrong:

• B (Sequential queues): Kafka uses partitions, not "sequential queues" - and ordering alone doesn't prevent duplicates.
• C (Deleting messages): Kafka is a log-based system; messages are retained, not deleted after consumption. Deleting them would break the ability for multiple consumers to independently read the same data.
• D (Retention periods): Retention controls how long messages are stored before expiry - it has nothing to do with tracking what's been processed.

Memory tip: Think of offsets like a bookmark in a book - your bookmark (committed offset) tells you exactly where you left off, so you never re-read pages you've already finished.

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